Many mobile electronic devices are designed to power down various circuit elements, or entire circuits, when not needed so as to conserve battery power. Some circuit elements with state, such as for example clocked flip-flops, may be part of a circuit that is powered down to save power. However, the memory of many such sequential logic circuit elements is volatile in the sense that it is lost by the circuit elements when they are powered down. When such circuit elements are turned back on, their state should be restored to what it was before they were powered down so that the mobile electronic device operates properly.
Accordingly, before powering down a sequential logic circuit element with volatile state so as to save power when it is not needed, the circuit element's state may be stored in non-volatile memory. When the circuit element is to be turned back on, its prior state may be recalled from the non-volatile memory and loaded into the circuit element. It is desirable that such store and recall operations are performed in a robust manner.